Fire-alarm signal-box for automatic telephone systems.



I J. ERIGKSON.

FIB-E ALARM- SIGNAL BOX FOB AUTOMATIC TELEPHONE SYSTEMS. v llPLIOA'TIOHFILED D150. 28 1911. RENEWED OCT. 4, 1913.

1,089,404. Patented Mar. 10, 19m

3 SHEETS-SHEET 1.

. Q 24 s- 5 1? a l 9 X Y PUSH I 121 l. ERIOKSON. FIRE ALARM SIGNAL BOXFOR AUTOMATIC TELEPHONE SYSTEMS. APPLICATION FILED DEC. 28, 1911.RENEWED 001. 4, 191a.

- 0 9 404 v Patented Mar. 10,1 -914.

3 SHEETS-8111131 2.

, J. ERIGKSON. FIRE ALABM-SIGRAL BOX FOR AUTOMATIC TELEPHONE SYSTEMS.LPPLIOATIOH FILED 17110.28, 1911. nmmwrzn 001.4. 1913.

1,089,404. Patented Mar. 10,1911 I a snnm snnn'r a. I? 5 amnion John itn s reams rarnnr ornion.

JOHN ERICKSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO DENIO GENERAL ELECTRICCOMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

FIRE-ALARM SIGNALBOX FOR AUTOMATIC TELEPHONE SYSTEMS.

Specification of Letters latent.

Patented Mar. 10,1914.

Application flled.December 28, 1911, Serial No. 668,223. Renewed October4, 1913. Serial No. 793,470.

To all whom it may concern:

Be it known that I, JOHN Emcxsox, of Chicago, in the county of Cook andState of Illinois, have invented certain new and useful Improvements inFire-Alarm Signal- Boxes for Automatic Telephone Systems; and I dohereby declare the following to be a full, clear, and exact descriptionof the same, reference being had to the accompanying drawings, forming apart of this specification, and to the reference-numerals markedthereon.

My present invention relates tosignal boxes for fire alarm systems, andhas for its object to provide an apparatus adapted particularly to beused in conjunction with those telephone systems in which the centraloffiee connections are set up or established automatically byelectromagnetically operated switching devices. The signal box orapparatus embodying my invention is adapted to actuate or automaticallycontrol the central ofiice switching mechanism to establish a connectionbetween a subscribers circuit and fire alarm headquarters, andthereafter to despatch the signal or ring in the number or code signalof the subscribers station at which the box is located.

My invention also has for its object to provide in conjunction withapparatus of this character, an electromagnetic device which is at alltimes associated with the subscribers circuit, having a movable partwhich will be actuated by the current on the line when the operation ofthe fire alarm box occurs during the period the subscribers circuit isbeing used for telephonic purposes, 'which will so control the operationof the box that the movement of its parts is arrested temporarily untilthe central office switches have been restored to their normal positionsby the subscribers act of hanging up their receivers.

To these and other ends the invention consists in certain improvementsand combinations of parts, all as will be hereinafter more fullydescribed, the novel features being pointed out in the claims. at theend of the specification.

In the drawings: Figure 1 is a front elevation of the mechanism of asignal box showing the operating parts constructed in accordance with mypresent invention and in their normal osition, thecasin of the box beingremdvec. Fig. 2 is a si e elevation;

F 1g. 3 is.a detail view of the gear train and the stop devices; Fig. 4is a detail View showing the several contact controlling members and thecooperating elements arranged to actuate them periodically; Fig. 5 is adetail view of the releasing push button or member, and Fig. 6 is adetail diagrammatic.

view showing the arrangement of the signal box in conjunction with anautomatic telephone system.

Similar reference numerals in the several figures indicate the sameparts. Fire alarm signals or call boxes embodymgmy present invention areemployed in coluunction with a subscribers circuit of a telephone systemfor despatching automatically a call or signal to fire alarmheadquarters. In those telephone systems in which the central ofiioeconnections are set up or established manually, a subscribers circuit isconnected to the fire alarm circuit by the central oiiice operator, anda signal is transmitted from the circuit thus established. In theautomatic telephone systems, where the central ofiice connections areestablished by the use of electro-mechanically operatedswitching-mechanism, the signal box must be provided with means fortransmitting the necessary impulses for effecting the switchingoperation to connect the subscribers fcircuit on which the signal box islocated with the fire alarm circuit, and after this circuit has beenthus established, the impulses of current for sounding the alarm orrecording the number of the signal box, are transmitted.

In automatic telephone systems the normal condition of the switches isrestored in readiness for subsequent operations only when one or both ofthe connected subscribers hang up or replace their receivers, andthereby grounding and then opening the line at the switch hook contactsof their respective instruments. F or the successful operation of a firealarm signal box t re, therefore, necessary when two subscribers linesare connected, that the first operat1on of the box shall produce such aneffect on the line that the subscribers will, of necessity, hang uptheir receivers, and that the box will thereafter take ossession of thesubscribers line on which 1t is arranged, so

that, if the subscriber, who was previously connected, or any othersubscriber, endeavors to make connection therewith, a condition the fan.At the opposite latter lies in the path of the projections 22, 22", asdo also the teeth of the spur gear 24. The latter is mounted upon a studshaft and is connected to a cam member having two different sets ofprojections and serving to rock the lever arms 26 and 27, which aresupported upon a common pivot 28, these levers controlling the openingand closing of 'various sets of contacts to effect the necessaryswitching operations at the central ofiice or exchange in conjunctionwith the movement the so called busy condition which is governed by afan 6 connected of the lever 21. The .lever 26 controls two thereto.Also mounted on the base 1 he sets of contacts a, b, and c, d, which arenorv neath the parts just described, is a restrainmally closed and heldclosed by the insulating device which may be released manually. ingmembers 26? and 26 engaging the In 1ts present formthe restrainingdevice springs a and a respectively. The lever 27 controls the movementof the spring a perniitting it to ply between the springs f and 9.Associated with thecontacts 0 and (Z is the third contact e' camsurfaces of the cam member, be fore referred to, which is movedintermittently by the spur'gear wheel 24, are arranged to producecoordinate operations between the varioussets of contacts by efshortlever arm 12, on the face of which appears the word Push, which isvisible through a sight aperture 13 in the cover 14, which incloses themechanism, and is removably attached to the base 1. v

The device-which restrains the operation of the clock train ispreferably arranged be- 6 in such position retracted by the and 27, ofFigs. 4 and 6.

The lever 21 carries at its upper end an insulating stud 21 whichengages the spring 2', and according to the direction of movement of thelever permits it to engage either end of the latter the spring 7' or thespring is parallel with is a finger or reed 15 attached to the armawhichis a fourth contact spring Z. ture 16 of a pair of polarizedelectromagnets he spring contacts of the box are ar- X and Y. The latterare supported in a ranged in the subscribers circuit of an autosuitableframe attached to the base 1, which inatic telephone exchange system, asshown also carries the pivot points of the armature in Fig. 6, and theirmovement is so con- 16 upon which is mounted a permanent trolled that atproper times they will by magnet 17. The relation of the coil windtheirconjoint action effect the necessary operation and vcontrol the centraloflice switching apparatus. this feature of the apparatus, there hasbeen and2, in which position the reed or finger shown in Fig. 6 well owntypes of 15 is held out of engagement with the fan switches, with whichthoseconversant with 6, this position being further assured, when theart of automatic telephony are familiar. the coils of the magnets arenot energized, In the arrangement of such switches at the by a delicatespring l8. central otfice,'they are divided into groups heoperatinganechanism of the signal or sets known generally as lineswitches, and box' urther comprises various contacts, as

first and second selectors and connectors, acshown in Figs. 1 and 6, andcooperating delines in the exvices for actuating them, said devicescomas the operation operating wheel 19and an of a plurality of switchesin setting up a alarm signal wheel 20, both mountedon the connection isgenerally the same as the o arbor 3, and a pivoted lever 21 controlled"eration of a single switch, inasmuch as they by the switch operatingwheel 19. The aroperate successively, there are merely shown bor 3 alsocarries an arm, sugiportmg at diafor convenience of illustration, twosubmetrically opposite points, ngers 22, 22, scribers-instrumentcircuits, the line swltch which, during the rotation of the arbor,percontacts of eachand a single selector and form a dual function uponeach half revoluconnector. The two subscribers circuits are tionthereof, first disengaging a trip lever indicated by R and V and R andV, these characters also indicating the vertical and rotary sides of therespective llnes. 1

Automatic switches of the character shown diagrammatically iaredisclosed in detail :-in

change to be served, but

asingle step. bemoticed, is provided with a extendingfinger 25, theextremity e trip, it will downwardly of which In order to illustrate 1Locate..-

U. S. Letters Patent, Nos. 815,176 2111(1815321, granted itlarch 13,1906, to Keith and Erickson, and. in the diagrammatic illust ation theselector switch S is shown as comprising a vertical and rotaryIIIOVtllJlQ shaft 30 carrying wipers or brushes 3, s, which will beiniderstood cooperate with the sets of contacts arranged in circularrows and vertical tiers, the shaft being movable vertically step by stepto aline the brushes with the different rows of contacts by means ofratchet mechanism actuated by what is known as the vertical magnet,indicated by V Similarly the shaft is revolved by a pawl and ratchetactuated by impulses of current transmitted through a. rotary magnet It,the respective circuits of said magnets being controlled by a contactarea w of the side switch mechanism actuated by the so-called privatemagnet i The switch arm "J normally. engages the contact a: whilecurrent impulses are transmitted to the vertical magnet, and when thesecease the confirming impulse transmitted from the rotary side of theline aotuates the side switch mechanism to step the switch arm intoengagement with the contact y, cutting in the rotary magnet and breakingthe circuit of the vertical magnet.

The side switch magnet is illustrated diagrammatically, comprising anari'naturc p of the magnet l? and carrying an arm and a spring ting -.rhaving offset ratchet teeth, which control the stepping along of theprojection 7) attached to the spring impelled switch arm a; to controlits stepping movement.

in the diagranunalic illustration in Fig. 6, the vertical and rotarysides of the subscribers telephone line are s leading from the w A s a.:Wlhrough the line switch contacts to the sub criber s telephone instrnniont A and the c lling' device B therefor. 'llhc calling derive.when employed for operating; the switch mcchanimn may, as hetore, be thewt known apparatus. and for these reasons d essential tion of the tchone system per so may be omitted. For this reason only those parts ofthe central ollicc switches have been shown which serve to illustrate heoperat in of the tire alarm signal. boy com -acted in accordance will.liIVOlllilOl'i and the objects atstood that many features; and detailsof the switching i'nechanh n. have been omitted, as we which. it-

necessary to t the Pl'llilllltlll! ph one sysi c'ni, si the art.

ation of an automatic lclccc. these are well known in oi: c ch mechagroundeo i for o at one side. as inni- *ating the seto the switch arm 20and other pole to the operai in connection with l to the Wire p leadingto the armatures o and 7* respectively, arranged in front of thevertical relay S and adapted to be attracted, when the latter isenergized, into engagement with the contacts of the wires c 1*, leadingrespectively to the vertical and rotary magnet Y R which latter are alsoconnected to the contacts a1, 2 of the side switch. The battery lead 72is connected by the wire 0 to the private magnet, the 11,- cuit of whichis completed by the wire p leading to the rotary line Wire R. The relay-S is connected by the wires 3 and s to one side of the battery and tothe vertical line wire V.

The connector switch mechanism indicated generally by T comprises thevertically movable and horizontally rcvoluble Wiper shaft 40 carryingthe brushes 2 t, which are con nected with the multiple contacts ortrunk terminals of the connector switch S by the wires V and R in whichare interposed the condensers C. The mechanism for operating the wipersi t of the connector switch operates to raise the wiper shaft andsubsequently rotate it after the selector switch has completed itsoperation and cut the line through to the connector switch. The lattercomprises the vertical magnet V, the rotary magnet R the vertical relayT, and the private magnet P. The battery X sups plies current for thecircuits of the several magnets just mentioned. In practice, the sideswitch mechanism before referred to, comprises a plurality of switcharms, preferably four in. number, each of which performs a differentfunction, but as these are well known I have only shown in F (3 two sideswitch arms 1.0 and t on the connector switch, the former for cutting insuccessively the vertical and rotary magnets, and the latter forsupplying ground or completing the battery connection when the connectorswitch wipers r, t have stopped their movement and connected with theproper outgoing line or called subscribefis circuit.

it is deemed a desirable feature in auto-' matic telephone practice toprovidemeans for supplying ljmttcry current to the line for talkingpurposes when the called subscriber answers in bv the act of removing,his reccivcr and (losing the switch contacts, and tamed thereby. itwill, tnereitore, be underi it willv be unrilcrstood that this act cutshack current for talking purposes to the calling subscribens end of theline. In accomplishing these objects there is asso eluted with theconnector switch a double wound rcla v N. 0. provided with an armai turcm. which. when. attracteifl, moves the contact spring m out ofengagement with p ied by the y y cw", one pole being; connected by thethe contact m into engagement with a contact at. One end of the coil Nis connected by the wire a to the wire V connected to the brush 1?;likewise one end of the coil 0 is connected by the wire 0 to the Wire Rlead 30 energizing of the coils N and O closes the ing to the brush t,said connections being on the called partys side of the condensers C.The other extremity of the coil of the magnet N is connected by the wiren to one side of the battery K and through the wire a it is alsoconnected to the conductor V of the calling partys circuit. A tap leadsfrom this wire if, as indicated by a to spring m The latter is normallyin engagement with the spring m, which is connccted by the wire m torotary -line wire R The circuit of the relay 0 is completed through theswitch arm t when the latter is in its third position of engagement withthe contact grounded by the wire 19, the switch arm being connected bythe wire 8 with one end of the coil of relay 0, and also joined to thespring m It will be understood from the foregoing description inconnection with Fig. 6 that the calling subscriber gets no current fortalking purposes until the called subscriber responds. hen theconnection is first made with the called subscribers line the live sideof the battery X is connected through coil N with the, called end of theline, the circuit being, completed to ground through the coil 0 and sideswitch arm 25 when the called party answers in. The

coils X, Y, are arranged in a branch circuit adapted at certain times tobe bridged across the subscribers instrument circuit, and for thisreason one end of the coil Y is connected bythe wire Y to spring Z, andthe other extremity of the coil X is connected by the wire Y with thespring h.

The cam member operated by the spur gear wheel 24 controlling the levers26 and 27 is provided with a series of surfaces controlling each of saidlevers to produce different combinations of circuits several ditierenttimes during each complete rotation of arbor 3, as will be seenfrom=inspection of the diagrammatic view in Fig. 6, which shows theparts in the normal position. The first movement of the spur gear wheel24: breaks the contacts of spring ab, cci. The signal box mechanismcontinues to run until the first projection on the wheel or member 19moves the lever 21 and closes to gether springs 1., is, Z. The act ofopening the sets of contacts cd, ab, cuts off the subscribers telephonecircuit on which this mechanism is installed, and the closing of thecontacts 5, 7tand Z grounds and short circuits said subscribers linethrough the polarized relay coils X, Y, the springs e, f and'c, 71-being closed at this moment. This grounding of both sides of the line issuflicient to effect the restoring of the central oflice switches,should it happen that the subscriber on this line was the-calling party,who, in order to converse with another subscriber, initiated the call.The next step in the operation is the'opening of the contacts e-f toremove the ground connection of the line above mentioned. The polarizedrelay coils X. Y then remain bridged. across the line through contacts7cl and h-c.

The third step is the breaking of the con tacts of the springs h-c toclear the line.

The fourth step consists in makingcontact between springs e-f to groundthe spring 2' after which the impulses over the vertical and rotarysides of the line may be transmitted to automatically effect theoperation of the central oflice switches. In this connection it will benoted that the wheel or contacts m, m connecting the battery X acrossthe calling end of the line.

In illustrating the switches, the means for releasing them has not beendisclosed, but it 35 will be understood however, that as soon as thecalling subscriber hangs up his receiver both sides of the line circuitare grounded at the subscribers station, which through agencies notshown, releases the connector 40 switch shaft permitting it to rotateand descend to its normal position. The con nector switch in doing thissubsequently causes each of the selector switches to be restored totheir normal positions as well as 45 the line switch.

Before proceeding with a detail description of the operation of the firealarm signal box, the detail connection of the various contacts will bedescribed.

50 The subscribers line or circuit wires V, R lead respectively to thecontact springs a, a, which are normally closed in engagement with thesprings d, b, the former leading to the instrument set over the wire dand the member 19 is provided with indentations which permit movement ofthe lever 21 so that spring i engages contact j to provide the necessaryvertical impulses and that said wheel has projections which cause thelever 5:5 latter over the wire 7). At the subscribers to move the spring2' into contact with /c, 12

station the calling device B is connected to whereby the necessaryconfirming impulse. ground by conductor B and by conductor or impulses,are despatched over the rotary B with the contact spring e. The fourconside of the line. In practiceit is customarytact springs i, j, 75 andZ are arranged in cirto provide the circuit leading to fire head- 60cuit as follows: Spring 1! is tied to spring 7' quarters with terminalson the first selector by wire 2' Spring j is connected to verticalswitch. and in Fig. 6 it is shown comprising line wire V by wire iSpring is is connectthe line wires E, F leading to the magnet G, ed bythe wire it" with rotary line wire R. controlling an armature in alocalcircuit of Vertical line wire Vis also connected with a magnet G bymeans of which a punch or as spring 9 by the wire 9. The polarized otherrecording device H may be operated to tan record the signal. 'After thecircuit E and F has been connected by the wipers s, s the group of'alarmindicating impulses are despatched by the successive opening and closingof the contact springs g-e, the former of which is moved laterally whenthe block of insulating material g cooperating with the wheel 20 ispermitted to drop into the indentations in the face of the wheel. Theoperation of the springs g and 6', just dc scribed, is known as thefifth step in the operation of the box mechanism, and at the time themovement of the spring 9 occurs the springs e and f are disconnected andspring 6 is in engagement with spring 9.

The sixth step consists in closing the contacts [Ir-(7 and c--f, alsocontacts a, is and Z. The circuits thus established prepare the selectorswitches at the central oiiice for their release.

The seventh step is the breaking of all. contacts to open all thecircuit connections allowing the full release of the selector 1switches.

The eighth movement of the cam members causes contact to be made betweensprings a b and ccl torestore the -subscribers telephone service.

In the event it is desired to despatch an alarm signal the push lever ormember 12 is operated to release the plunger 7, which is then retractedby the spring 10, and the es capement 6 then being free to vibratepermits the driving devices of the signal box to begin their operation.A partial revolution 5 of the arbor 3 causes the projection 22 to liftthe trip and impart one'step'to the 1 gear wheel 24. The first operationof the cam member then cuts off the telephone subscribers instrument,and short circuits and grounds the line through the polarized relay.coils X, Y. If the subscriber on whose line the box is installed isusing his telephone circuit and has been the calling subscriber, whoinitiated the previous call and set up the connection, the mechanismofthe box is able to release the existing switch connections, and nopause ordelay occurs in the operation of the signaling mechanism.However, should a telephone connection have been previously establishedfrom some other telephone to the circuit, upon which the signal box isinstalled, the operation of the box will not release the circuit, and itis necessary, therefore, to arrest the movement of the signalingmechanism, until the switches have been restoredto their normalcondition, and to provide means so that when this restoratioh of thelines has occurred the box will automatically be released and permittedto perform its functions in the usual manner. To this end theeleetromagnets X and Y are brought into the circuit.

In practice when a fire alarm mechanism is installed upon a sub'scribersline a re versal is made in the wires between the connector terminalcontacts and the line switch normal contacts, so that when a calloriginates on the box subscribers telephone circuit, and the connectionis established, there is negative battery on the vertical side of theline and positive battery on the rotary side of the telephone line,consequently inevery connection made to this line the battery whensupplied, for talking purposes is con nected through the connectorswitch at its negative side to the rotary wire and at its positive sideto the vertical wire. Therefore, when the signal box mechanism isoperated after the subscriber has been called by some other party, theflow of battery currentthrough the coils X, Y is in such a direction asto attract the armature 16, so as to move the finger or reed 15 intoengagement with the fan 6. Now when this condition exists the calledsubscriber has been cut off and the calling subscriber finding that hisconnection has been disturbed hangs up his receiver and by so doingrest-ores his own selector switches, upon the release of which thecurrent supplied through the connector switch to the telephone line isremoved; thereupon the polarized armature 16 as sumes its normalposition, the driving mechanism of the signal box continues to run on,and during this movement actuates the central ofiice switches to pick upthe fire headquarters circuit and record the alarm signal. The latter ispreferably despatched several times in, succession and after the lastround of the box the subscribers telephone circuit is restored to itsnormal condition.

I claim as my invention:

1. In a signal mechanism for use on a subscribers circuit of anautomatic telephone system comprising central ofiice switching mechanismfor connecting two subscribers circuits, the combination with amechanism for transmitting current impulses l'o effect the operation ofthe switching mechanism embodying driving devices.

of means for restraining the operation of the driving devices comprisinga polarized armat-iu'e adapted to be influenced and moved into arrestingposition by the current supplied to the line when two subscriberscircuits are connected for conversational purposes.

2. In a fire alarm signal mechanism, for subscribers circuits of anautomatic telephone exchange con'iprising automatic central oiliceswitching mechanism and circuit arrangements for cutting back batterycurrent for talking purposes when the called party answers, thecombination with mechanism for controlling the switches to set up aconnection between two circuits, devices for driving stud mechanism andmeans ing its operation,

which is normally inoperative for restraincomprising an armature, andelectro-magnet adapted to be bridged across the subscribers circuit whenthe signalmechanism has been started and to be energized when saidcircuit has been connected to another subscribers circuit, and means foropening the first mentioned subscribers circuit after said magnet hasbeen energized.

3. A signal apparatus adapted to be used on a subscribers circuit of anautomatic telephone exchange, comprising a driving mechanism, meansoperated thereby for transmitting current impulses to actuate thecentral office switches to connect two subscribers circuits, andsubsequently despatch alarm recording impulses, ing said drivingmechanism comprising polarized electro-magnelic devices adapted to beactuated into arresting position by the current in the line when twosubscribers circuits are connected and to be actuated into releaseposition when said circuits are disconnected.

4. An alarm system apparatus for use on subscribers circuits ofautomatic telephone systems, comprising means for despatching impulsesfor operating the central office switches and other impulses forrecording an alarm, and devicesnormally set for driving'said means, apolarized electro-magnetadapted to be bridged across the'line when thedriving devices are operated, an armature which is moved in a directionto control the driving devices when said magnet is energized by currentof one polarity.v

5. In an alarm signal apparatus for use on subscribers circuits ofautomatic tele-- phone systems, the combination with means fortransmitting the operation of and despatch a current impulses to effectthe central oflice switches signal over a line subsemeans for arrest- 5quently connected by the switches and devices for driving said means, ofsets of contacts and members operated by the driving devices controllingthem for opening the subscribers instrument a branch circuit bridgedthereto having an electro-magnet therein, ture on said magnet andthereby for restraining the driving devices normally held in aninoperative position and moved into an operative position by the flow ofcurrent employed for talking purposes when a called subscriber hasanswered.

In a signal box'mechanism the combination with driving devices having anescapement, impulse despatching members moved thereby and sets ofcircuit contacts operated by said' members, of a plurality of a memberoperated Copies of this patent may he obtained for five cents each, byaddressing the other sets of contacts, membersfor moving them, aplurality of revoluble cams con trolling said members and meansintermittently operated by saiddriving devices for rotating the camsrelatively to the movement of the impulse despatching members.

In a signal. box mechanism the combination with driving devices havingan escapement, impulse despatching members moved thereby and sets ofcircuit contacts operated by said members, of a plurality of other setsof contacts, members for moving them, a plurality of revoluble camscontrolling said members, a driving member for rotating the cams and alocking device for said member, an operating device moving with theimpulse despatching members and intermittently releasing the lockingdevice and rotating the driving member a partial revolution.

8. In a signal box mechanism the combination with driving devices havingan escapement, impulse despatching members moved thereby and sets ofcircuit'contacts operated by said members, of a plurality of other setsof contacts, members for moving them, and means controlling their movement relatively to the movement of the impulse despatching members,polarized electro-magnets having'a circuit controlled by one of saidsets of contacts, an armature for said magnets and a member controlledthereby and cooperating with the driving devices to either restrain orpermit their operation.

9. The combination with an automatic telephone exchange system in whichthe C011- nection between two subscribers circuits is set up byautomatic switching mechanism and current for talking purposes is cutback when the called subscriber answers, and the switches are restoredto normal when the calling party hangs up of a signal mechanismcomprising means for despatching current impulses to operate theswitches and transmit impulses for recording a signal and devices fordriving said means, a polarized clectro-magnetic mechanism for arrestingsaid driving devices comprising a branch circuit adapted to be bridgedacross the subscribers line after the driving de vices have commencedtheir operation, and also adapted to be actuated by the talking currentto arrest said devices and in the subscribers line adapted to be openedto disconnect said line upon commencement of the movement of the drivingdevices.

JOHN ERIOKSON.

Commissioner of Patents,

Washington, D. 0.

